You may find this helpful to understanding persistantAggregate works internally.
http://svendvanderveken.wordpress.com/2013/07/30/scalable-real-time-state-update-with-storm/ -Cody On Tue, May 27, 2014 at 1:53 PM, Danijel Schiavuzzi <[email protected]>wrote: > The aggregations are done by Storm. persistentAggregate provides only a > means to access the datastore to get the current aggregate for the > specified key (using the IBackingMap's multiGet() implementation), > provide that aggregate as the input to the Aggregator implementation along > with other same-keyed tuples in the current batch (the > groupBy/GroupedStream), and persist it back to the database using > multiPut(). > > > On Tuesday, May 27, 2014, Raphael Hsieh <[email protected]> wrote: > >> From my understanding, PersistentAggregate should first aggregate the >> batch, then once the batch has finished aggregating, send it to whatever >> datastore is specified. >> >> Is this the case ? Or will the Persistent Aggregate use the external >> datastore in order to do the aggregations ? >> >> -- >> Raphael Hsieh >> >> >> > > > -- > Danijel Schiavuzzi > > E: [email protected] > W: www.schiavuzzi.com > T: +385989035562 > Skype: danijels7 > -- Cody A. Ray, LEED AP [email protected] 215.501.7891
